对碘量法测定日粮、肠道食糜及排泄物中半胱胺盐酸盐含量的改进研究

试验旨在探讨碘量法测定日粮、食糜及排泄物中半胱胺盐酸盐(cysteamine hydrochloride,CSH)含量的改进方法,为评估包膜CSH在动物胃肠道内释放过程中CSH的定量提供参考。试验分3部分:试验一:检验包膜CSH的上样量对碘标准液消耗量的线性关系,以确定碘量法检验包膜产品的准确度,采用单因素完全随机设计,CSH的上样量设6个水平,分别为28.28、113.12、226.24、339.36、452.48和565.61mg;试验二:考察H2SO4预处理对消除日粮、食糜和排泄物对碘量法测定CSH含量的影响,采用单因素完全随机设计,日粮、十二指肠食糜、空肠食糜、回肠食糜及排泄物样品中CSH(试剂级)的含量均设3个水平,即30、100和300mg/2g,形成15个含有CSH的样品,H2SO4溶液(6mol/L)设3个水平,即0.1、0.5和1mL,每个处理设3个重复;试验三:考察传统碘量法与试验二建立的改进方法在测定日粮、食糜及排泄物中包膜CSH含量的差异,采用两样本试验设计,日粮、十二指肠食糜、空肠食糜、回肠食糜及排泄物中CSH的含量均设28.73、84.84、141.47和200.56mg/2g。结果表明:①CSH的上样量对碘标准液消耗量及CSH测定值均呈显著的线性关系(P<0.01,R2=0.9999)。②在含有CSH的日粮中,H2SO4溶液处理后由碘量法测定的CSH质量对实际质量的回归均符合Y=X(P>0.05)。在含有CSH的十二指肠食糜和回肠食糜中,所有H2SO4溶液处理下CSH质量对实际质量的回归均不符合Y=X(P<0.05),但0.5和1.0mL比0.1mL H2SO4溶液处理使测定值更接近实际值。在含有CSH的空肠食糜及排泄物中,0.5和1.0mL H2SO4溶液处理使测定值对实际值的回归符合Y=X(P>0.05),而0.1mL H2SO4溶液处理下CSH测定值显著低于实际值(P<0.01)。③在含有CSH的日粮、十二指肠食糜、空肠食糜、回肠食糜及排泄物样品中,常规方法测定的CSH对实际质量均偏离Y=X(P<0.05),而1.0mL H2SO4溶液处理后的测值对实际质量均符合Y=X(P>0.05)。由此可见,采用适量H2SO4溶液进行处理后,可以排除日粮、食糜及排泄物对CSH测定的干扰。

Study on Improved Method of Iodimetry for Determination of Cysteamine Hydrochloride in Diets,Intestinal Digesta and Excreta

This experiment was conducted to improve the method of iodimetry for the determination of cysteamine hydrochloride (CSH) in diet,digesta,and excreta,which will be used to assay the CSH for evaluating the releasing process of encapsulated cysteamine in gastro-intestine of animal.Experiment 1 was to examine the linear relationship between iodine consumption on the amount of CSH with the iodimetry.Six levels of 28.28,113.12,226.24,339.36,452.48,565.61 mg of CSH was adopted in a single-factor completely randomized design.Experiment 2 was to investigate the effect of pretreatment on eliminating interference from diet,digesta and excreta in the determination of CSH with iodimetry.Fifteen samples were composed that in each 2 g of diet,duodenal digesta,jejunaldigesta,ilealdigesta or excreta of chicken,the amounts of CSH (reagent grade) were 30,100 and 300 mg.The volume of 0.1,0.5 or 1 mL of 6 mol/L sulphuric acid solution was adopted in single-factor completely randomized design to pretreat each sample.Experiment 3 was to test the differences between conventional iodimetry and the improved method established in the experiment 2 to determine CSH in diet,digesta and excreta.The amounts of CSH (provided by the encapsulated product) of 28.73,84.84,141.47 and 200.56 mg were mixed in each 2 g of diets,duodenal digesta,jejunaldigesta,ilealdigesta,and excreta of chicken.A two-sample experimental design was adopted to compare 2 methods to determine the content of CSH.The results showed as follows:①There was a significant linear relationship between the iodine consumption or the determined CSH on actual amount of CSH (P<0.01,R²=0.9999);② In the diet mixed with CSH,sulfuric acid pretreatment for iodimetry made the regression of determined on actual amount of CSH consistent with Y=X (P>0.05).In the duodenal or ilealdigesta mixed with CSH,sulfuric acid pretreatment for iodimetry didn't made the regression of determined on actual amount of CSH consistent with Y=X (P<0.05),however,the pretreatment with 0.5 or 1 mL sulfuric acid made the determinred value closer to the actual value than the pretreatment with 0.1 mL.In the jejunaldigesta or excreta mixed with CSH,sulfuric acid pretreatment made the regression of determined on actual amount of CSH consistent with Y=X (P>0.05),whereas,the pretreatment with 0.1 mL sulfuric acid made the determined value significantly lower than actual value of CSH (P<0.01).③In diet,duodenal,ileal and jejunaldigesta or excreta mixed with CSH,conventional method made the regression of determined on actual amount of CSH deviate from Y=X (P<0.05),whereas,pretreatment with 1.0 mL sulfuric acid made the regression of determined on actual amount of CSH consistent with Y=X (P>0.05).In conclusion,pretreatment with an appropriate amount of sulphuric acid solution cculd improve the determination of CSH by eliminating the interference from diet,digesta or excreta.